| 162 | } |
| 163 | |
| 164 | double Histogram::StandardDeviation() const { |
| 165 | if (num_ == 0.0) return 0; |
| 166 | double variance = (sum_squares_ * num_ - sum_ * sum_) / (num_ * num_); |
| 167 | return sqrt(variance); |
| 168 | } |
| 169 | |
| 170 | std::string Histogram::ToString() const { |
| 171 | std::string r; |